Ti和正火工艺对Nb-V-Ti微合金电机轴用钢16MnT低温冲击韧性的影响

Effect of Ti and Normalizing Process on Low Temperature Impact Toughness of Nb-V-Ti Microalloying Steel 16MnT for Motor Shaft

试验16MnT钢(/%:0.14~0.15C,0.27~0.30Si,1.40Mn,0.008~0.010P,0.003~0.004S,0.020~0.025Nb,0.10V,0.002~0.08Ti,0.025~0.027Al,0.0043~0.0053N)的生产工艺流程为60t EAF-LF-VD-5.8t铸锭-锻造φ190~250mm棒材-920℃正火。检验结果表明,0.08%Ti 16MnT钢锻造正火后-20℃冲击功为6~16J,低于标准值34 J。分析结果得出,0.08%Ti钢中存在大量TiN和延晶Nb-Ti(C,N)析出相,-20℃钢的断口为典型沿晶脆性断裂,且锻材断面的组织不均匀,表面为索氏体,心部为铁素体+珠光体。通过将钢中Ti含量降至0.002%,正火风雾冷却时锻材间距离为1.5m,使16MnT钢锻材的-20℃冲击功提高至132~288 J。

The production process flowsheet of tested steel 16 MnT（/% ： 0. 14~0. 15 C, 0.27~0.30 Si,1.40 Mn,0.008~0. 010 P,0.003~0.004 S,0.020~0.025 Nb,0. 10 V, 0.002~0.08 Ti,0.025~0.027 Al,0.004 3~0.0053 N）is 60 t EAF-LF-VD-5. 8 t ingot casting-φ190~250 mm forging-normalizing at 920℃. Examination results show that the impact energy of forged-normalized 0. 08%Ti steel 16 MnT at-20℃ is 6~16 J,it is lower than the value of standard requirement-34 J. The analysis results obtain that large amount TiN and along grain boundary precipitated phase NbTi（C,N） exist in 0. 08%Ti steel and the fracture of steel at-20℃ is typical brittle fracture along grain boundary, and the structure of forged product section is non-homogeneous, at surface it is sorbite while at centre of section it is ferrite ＋pearlite. With decreasing the Ti content in steel to 0. 002% and controlling the 1. 5 m distance between forgings during normalizing wind-fog cooling process, the impact energy of forged product of steel 16 MnT at-20℃ increases to 132 ~ 288 J.